This invention relates to a bus interface system/apparatus for coupling digital audio, video and data processing systems, and in particular to coupling signals for control of recording apparatus.
The advent of digitally compressed audio and video transmission systems, such as the Grand Alliance HDTV system for terrestrial high definition television broadcasting, or the DirecTV(trademark) direct broadcast satellite TV system currently employing the NTSC system, demonstrate that virtually studio quality audio and video signals can be delivered to a viewing audience. However, such exemplary quality signals are instantly degraded when time shifted for later viewing by means of currently available consumer analog recording formats, for example, VHS, S-VHS, 8 mm and Hi 8.
The introduction of consumer quality digital video recording cameras, for example DVC, demonstrates that consumer quality digital recording may yield sound and picture quality virtually indistinguishable from the original material. Other consumer products are emerging, for example, D-VHS, video disc, DVD, digital cameras, scanners and computers with digital processing capabilities which permit multiple generation digital signal dubbing, copying, replicating or editing, with sound and picture quality remaining essentially equal to that of the original recorded source. The high levels of technical quality and performance delivered by such consumer digital equipment raises concern with respect to copyright infringement by unauthorized copying. Proposed legislation in the form of the xe2x80x9cVIDEO HOME RECORDING ACT of 1996xe2x80x9d requires that digital audio/video signals include copy protection information to allow the copyright owner to determine and control the audience size viewing the copyrighted material. Implementation of copy protection requires that copy control information be included with or within the copyrighted material and be maintained throughout subsequent processing procedures. In addition such copy control information may be amended as a result of subsequent processing to retain control the copyright owner""s intellectual property. A digital recording device is disclosed in EP A 0 498 617 which extracts copy control data from an input data stream to control recording and to amend copy contol data subsequent to recording. A further digital recording device is disclosed in EP A 0 717 564 which accepts an MPEG bit stream containing a PES header which includes copyright and copy control data. The recording device decodes and decrypts copy prevention information and in response thereto encrypts the bit stream for recording. A second embodiment disclosed in EP 0 574 892 is directed to copy control by means of information superimposed in one horizontal period of the vertical blanking interval of an analog video signal.
In an inventive arrangement, an apparatus processes a source of compressed digital audio, video and control data occurring in transport packets. The apparatus comprises a deriving means responsive to the source for deriving copy control data from the transport packets. A generating means responsive to the copy control data for generating a copy control word. A forming means for forming a superpacket including the copy control word and the transport packets. In a further inventive arrangement copy control information is derived from a packetized source and processed for coupling via a control data bus. In another inventive arrangement a replicating device receives the formatted transport packet with copy control header and responsive to the copy control information initiates replication and amends the copy control header to preclude any further copying of the formatted transport packet and copy control header. In yet another inventive arrangement a replicating device receives the formatted transport packet and copy control header and the copy control information from a control data bus. The replicating device implements commands contained in the copy control information only if the copy control information from the two sources correspond. In yet a further inventive arrangement a replicating device periodically receives copy control information from a control data bus and absent said periodic reception assumes a copy prohibited status. Another inventive arrangement controls a replicating device responsive to copy control information such that a copy is made but simultaneous transport packet decoding for viewing is precluded.